The present invention relates to a process for producing a tetraalkylthiuram disulfide. More specifically, it is concerned with a process for producing a tetraalkylthiuram disulfide which comprises directly obtaining the tetraalkylthiuram disulfide by electrolyzing a secondary amine having an alkyl group containing from 1 to 4 carbon atoms and carbon disulfide in an electrolytic solvent consisting of any suitable solvent in the presence or absence of any suitable supporting electrolyte.
By way of example, one conventional industrial process for producing a tetraalkylthiuram disulfide which is used as a vulcanization-accelerator or vulcanizing agent for rubbers comprises reacting a dialkylamine with carbon disulfide at a low temperature in the presence of an aqueous solution of sodium hydroxide to form an aqueous solution of sodium dialkyldithiocarbamate, refining the aqueous solution, adding by dropping sulfuric acid and hydrogen peroxide as an oxidizing agent to the resulting aqueous solution to neutralize the same, oxidizing the dialkyldithiocarbamate acid resulting from the neutralization simultaneously with the neutralization, filtering the precipitate of the resulting product, tetraalkylthiuram disulfide, washing the same with water, dehydrating and drying the same, and crushing the same, if necessary.
Furthermore, in the oxidative dimerization of sodium dialkyldithiocarbamate, in addition to the above mentioned hydrogen peroxide, use has been made, as an oxidizing agent, of nitrogen dioxide (NO.sub.2), chlorine (Cl.sub.2), bromine (Br.sub.2), iodine (I.sub.2), ozone (O.sub.3), oxygen (O.sub.2), sodium nitrite (NaNO.sub.2), sodium hypochlorite (NaOCl), sulfur monochloride (S.sub.2 Cl.sub.2), sulfur dichloride (SCl.sub.2), potassium perbromate (KBrO.sub.3), selenic acid (H.sub.2 SeO.sub.3), and ammonium persulfate [(NH.sub.4).sub.2 S.sub.2 O.sub.8 ]. All of the processes using these oxidizing agents require a stoichiometric quantity of an oxidizing agent and a neutralizing agent, and the use of these chemicals requires special handling caution with regard to the reaction apparatus, the incidental apparatus, and process control.
In addition, in order to reduce or eliminate the use of chemical reagents such as a neutralizing agent, a process for oxidizing directly a dialkylamine and carbon disulfide in a solvent of water to convert them into a dialkylthiuram disulfide has also been devised. In this case, hydrogen peroxide, potassium perbromate, oxygen-cobalt phthalocyanine disulfonate, oxygen-iron (or cobalt or nickel) phthalocyanine carboxylate and the like are used as an oxidizing agent.
All of these conventional processes are not fully satisfactory in that not only is an oxidizing agent or oxidizing catalyst required, but the production processes are also significantly complex and, as a result, side effects occurring during the oxidation reaction cannot be avoided. For this reason, it is necessary to simplify the complex production process causing many problems with regard to the control of production and, at the same time, to remove the pollution due to waste water caused by by-products. In this connection, there is also an urgent demand for the reduction of the large sum of equipment investment required for the treatment of waste water and the treatment cost.